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In this paper, the tribological behavior of nanoeutectic Fe1.87C0.13 alloy and its coarse-grained-eutectic counterpart under air and vacuum was investigated. The results showed that the wear rate of both alloys was lower in air than in vacuum, and their friction coefficient was related to applied load and testing atmosphere. The nanoeutectic Fe1.87C0.13 alloy exhibited lower wear rate than the coarse grained counterpart in both environments. The wear rate of both alloys increased but the friction coefficient decreased with increasing applied load under both air and vacuum. The dominant wear mechanisms were adhesion wear in vacuum but oxidation wear along with slight delamination in air. [ABSTRACT FROM AUTHOR]

This article presents a new solution for the lubrication and wear problem of TiAl alloy in vacuum by coating Ti3AlC2 layer. Ti3AlC2 coating and Ti‐46Al‐2Cr‐2Nb alloy substrate are simultaneously consolidated by hot‐pressed approach. The coating demonstrates superior self‐lubricity, CoF of 0.2 and negligible wear, in the vacuum of 2.0 × 104 Pa. A transition layer is formed in the interface, resulting in very strong coating adhesion. [ABSTRACT FROM AUTHOR]

Abstract: Binderless TiC–WC–Cr3C2 hard materials with different compositions were prepared by FAST (field-assisted sintering technique) and by SPS from mixtures of TiC, WC and Cr3C2. The effect of the microstructure on the properties was evaluated in as-densified materials and materials heat treated at 1900°C. The mechanical properties were determined and the microstructures were characterised using X-ray diffraction and scanning electron microscopy. A cubic (Ti, W, Cr)C phase was found to form during sintering. Hardness values of up to 23GPa were observed. For the TiC-rich materials annealing did not have a significant effect on the hardness, but in the case of the WC-rich materials it resulted in a reduction in the hardness due to pore formation. [Copyright &y& Elsevier]

Abstract: Bulk novel cemented carbides (W1− x Al x )C–10.1vol% Co (x =0.2, 0.33, 0.4, 0.5) are prepared by mechanical alloying and hot-pressing sintering. Hot-pressing (HP) is used to fabricate the bulk bodies of the hard alloys. The novel cemented carbides have good mechanical properties compared with WC–Co. The density and operating cost of the novel material is much lower than a WC–Co system. The material is easy to process and the processing leads to nano-scaled, rounded, particles in the bulk material. The hardness of (W1− x Al x )C–10.1vol% Co (x =0.2, 0.33, 0.4, 0.5) hard material is 20.37, 21.16, 21.59 and 22.16GPa, and the bending strength is 1257, 1238, 1211 and 1293MPa, with the aluminum content varying from 20% to 50%. The relationship between the microstructure and the mechanical properties of the novel hard alloy is also discussed. [Copyright &y& Elsevier]

Abstract: A novel nano-scaled bulk hard material (W0.5Al0.5)C–Co with “rounded” grains was prepared by nanocrystalline “rounded” (W0.5Al0.5)C powders with “rounded” particle shape in this study. The nano-scaled “rounded” particles do not contain sharp edges, which form local tensile stress concentrations on loading of the composite, thus leading to improved toughness and reduced sensitivity to crack. Nanocrystalline (W0.5Al0.5)C powders with “rounded” particle shape were used as starting materials. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to characterize the samples. The novel hard material has superior mechanical properties; it possesses high hardness (25.36GPa), high bending strength (2213MPa), and lower density (9.360gcm−3) compared with the common hard material (WC–Co). The formation mechanism of the “rounded” (W0.5Al0.5)C particles, and the relationship of the mechanical properties and the microstructures are also discussed. [Copyright &y& Elsevier]

Abstract: A novel cemented carbides (W0.5Al0.5)C0.8–Co with different cobalt contents were prepared by mechanical alloying and hot-pressing technique. Hot-pressing technique as a common technique was performed to fabricate the bulk bodies of the hard alloys. The novel cemented carbides have superior mechanical properties compared to WC–Co. The density, operating cost of the novel material were much lower than WC–Co. There is almost no η-phase in the (W0.5Al0.5)C0.8–Co cemented carbides system although the carbon deficient get the value of 20%, and successfully got the nanostructured rounded (W0.5Al0.5)C0.8 particles. [Copyright &y& Elsevier]

Abstract: Pure (W0.4Al0.6)C powder of about 1μm in diameter was sintered by the high pressure sintering (HPS) process without the addition of any binder phase. The microstructure, Vickers micro hardness and density versus the sintering time and temperature are well described. The most suitable sintering condition under pressure of 4.5GPa is 1873K for 8min. Under this sintering condition, the hardness can reach 2295kgmm−2 and the relative density can reach 98.6%. [Copyright &y& Elsevier]

Ni-based composite coatings reinforced by TiB X /Ti X Ni Y /TiC with different Ti6Al4V contents were precipitated on a 35CrMoV substrate via laser cladding. The phase composition, elemental distribution, and precipitated phases of the coatings were characterised using X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy. The mechanical and tribological properties of the cladding layer were also characterised. The results showed that the coating contained TiB 2 , TiC, TiB, Ni 3 Ti, and NiTi 2 phases with uniform elemental distribution and grain refinement. A schematic of the growth model and precipitation sequence of the reinforced phases was generated. The microstructure, elemental segregation, hardness, and friction behaviour of the cladding layer were significantly influenced by the addition of Ti6Al4V. The optimal microstructure and best mechanical properties were obtained by the addition of 4 wt% Ti6Al4V, with that coating possessing a hardness, average friction coefficient, and wear volume of 770.8 HV 1 , 0.180 and 6132 um3, respectively. [ABSTRACT FROM AUTHOR]

Implant materials with micro/nanostructures bear a closer resemblance with the features of natural bone, which influences the wettability, bone differentiation, and vascularization of materials. However, it is still technically challenging to design the inner wall and surface micro/nanostructures on macroporous bioceramics due to their brittleness. In this work, micro/nanostructured composites with Si3N4 whiskers as a framework, and the (inner) surface covered with SiC nanowires were prepared, denoted as SiC‐nw@Si3N4‐w bioceramics. The synthesis, adopting the green chemistry concept, was utilized from environmental products (carbon evaporated in the furnace at high temperature) and reaction impurities (carbon obtained by polymer pyrolysis and silicon obtained by Si3N4 decomposition) to synthesize SiC nanowires via a vapor‐solid growth mechanism. The prepared SiC‐nw@Si3N4‐w bioceramics have potential applications in bone repair due to their cell adhesion and proliferation. [ABSTRACT FROM AUTHOR]

The inherent brittleness and uniform coloration of Si 3 N 4 materials have traditionally limited their applicability. In this study, colored Si 3 N 4 ceramics were synthesized utilizing α-Si 3 N 4 powder, a ternary mixture of sintering additives, and rare earth oxides (Eu 2 O 3 , Dy 2 O 3). The study focused on assessing the influence of varying Dy 2 O 3 content and holding time on the coloration, mechanical properties, and electromagnetic shielding properties of Si 3 N 4 ceramics. The incorporation of Eu 2 O 3 induced a color shift from gray to yellow-green, while the addition of Dy 2 O 3 facilitated the regulation of brightness in yellow-green Si 3 N 4 ceramics. The results reveal that both hardness and bending strength decreased with prolonged holding time, correlating with changes in sample density. The addition of rare earth oxides can effectively improve the fracture toughness of the Si 3 N 4 ceramics. Specifically, under conditions of 45 min holding time, 2%SED exhibited the highest fracture toughness at 8.45 MPa·m1/2. This enhancement can be primarily attributed to extended retention time, resulting in increased β- Si 3 N 4 phase content, improved fracture energy absorption, and a larger aspect ratio. The introduction of Eu 2 O 3 and Dy 2 O 3 did not significantly alter the electromagnetic shielding properties of Si 3 N 4 ceramics. This study offers novel pathways for the application of Si 3 N 4 ceramics in emerging fields. [ABSTRACT FROM AUTHOR]

Abstract: A novel hard material of (W0.25Al75)C has been successfully prepared by the high-pressure sintering process without the addition of any binder phase. The high-pressure is a suitable and powerful technique for sintering the binderless hard material, the relative density of the hard material can reach 99.6% under high-pressure sintering. The density of the novel light hard material is only 6.2371gcm−3, which is much lighter than the normal hard material. The hardness of the light hard material can reach 18.89GPa even the aluminum content get the astonished 75%. [Copyright &y& Elsevier]

The applications of Si 3 N 4 ceramics are hindered by their brittleness and susceptibility to fracture, despite their high strength and wear resistance. To address this challenge, layered ceramics were prepared using lamination and plasma sintering techniques, inspired by the structure of shell pearl layers. The bio-inspired layered ceramics were alternately arranged with Si 3 N 4 as the matrix layer (hard) and BN as the interfacial layer (soft). During the study, ceramic specimens with different microstructures were obtained by modulating the layer thickness ratio (ratio of Si 3 N 4 to BN) and sintering temperature. The microstructure of the specimens was characterized using SEM (Scanning Electron Microscope) and EDS (Energy Dispersive Spectrometer). The mechanical of various specimens were assessed by measuring the flexural strength and fracture toughness. The results of the investigation revealed that the mechanical characteristics of the samples reached their optimum state (with a toughness of 13.51 ± 1.56 MPa m1/2 and a strength of 429 ± 4.28 MPa) when the ratio of Si 3 N 4 to BN was 5:1, and the sintering temperature was maintained at 2000 °C. [ABSTRACT FROM AUTHOR]

In this work, a novel Cu/AlMgB14 composite was prepared by hot-press sintering, and its tribological responses to the AlMgB14 content and sintering temperature under deionized water and liquid paraffin media were investigated. As the results show, the wear resistance of pure copper is greatly enhanced by adding AlMgB14 in both media. Besides, the Cu/AlMgB14 composites sintered at lower sintering temperature show better lubricating irrespective of the AlMgB14 content due to the porosity of the specimens, while those sintered at higher temperature show gradually improved wear resistance with the AlMgB14 content increasing due to the growingly improved hardness. In addition, in liquid paraffin, a lower COF and a comparable wear rate to that in deionized medium are obtained due to the hydrophobic and lipophilicity of the composites. [ABSTRACT FROM AUTHOR]

This study involved the synthesis of Si 3 N 4 ceramics, focusing on adjusting TiN content and sintering temperatures to enhance mechanical properties. Utilizing Density Functional Theory (DFT), we examined the microstructure and elastic properties of Ti-doped β-Si 3 N 4 , providing insights into how the Ti atom influences mechanical behavior. Additionally, a machine learning approach was applied to establish a predictive model for Si 3 N 4 fracture toughness, factoring in material composition and the sintering process. Remarkably, TiN incorporation led to a substantial increase in hardness, reaching 16.63 GPa. At 1800 °C, the resulting material at 10 wt% and 5 wt% TiN content exhibited impressive flexural strength (924 MPa) and fracture toughness (8.48 MPa m1/2). The theoretically calculated elastic properties confirmed the benefits of Ti atom doping in enhancing Si 3 N 4 ceramics. By employing the relu activation function in combination with the rmsprop optimizer, we achieved a coefficient of determination (R 2 ) for the test set no less than 0.824, ensuring reliable predictions for TiN–Si 3 N 4 fracture toughness. This study provides valuable guidance for swiftly predicting high-performance Si 3 N 4 ceramics and introduces a novel research avenue for the development of advanced materials. [ABSTRACT FROM AUTHOR]

The repair and functional reconstruction of bone defects had become an urgent need and an important research topic. To repair bone defects, artificial bone materials must have an interconnected microporous structure to match the defect site with sufficient mechanical strength and good biocompatibility. To fulfill these requirements, a continuous porous Si 3 N 4 ceramic with high strength and toughness, low friction and good biological properties was prepared. The particle-stabilized foam provided a controlled hierarchical porous structure, whereas the in situ growth of β-Si 3 N 4 grains during sintering not only enhanced mechanical strength to meet practical applications in tissue engineering scaffolds but also changed the surface chemistry of pores to improve biocompatibility. These attractive properties promoted porous Si 3 N 4 ceramics with advanced applications in bone defect repair. [ABSTRACT FROM AUTHOR]

• Exogenous H 2 S suppressed cell proliferation, migration and cell cycle progression in melanoma cell lines. • Exogenous H 2 S induced apoptosis in melanoma cell lines. • Exogenous H 2 S promotes autophagy in melanoma cell lines. • Suppression of autophagy inhibited melanoma cell development. • Exogenous H 2 S inhibited melanoma via suppression of PI3K/AKT/mTOR signaling pathway. : Melanoma is one of the most aggressive, therapy-resistant skin cancers in the world. Hydrogen sulfide (H 2 S), a newly discovered gasotransmitter, plays a crucial role in the progression and development of many types of cancers. However, the effect of H 2 S on human skin melanoma remains to be elucidated. : We aimed to explore the effect of exogenous H 2 S on melanoma cells and its underlying mechanisms. : In this study, human skin melanoma cell lines, including A375 and SK-MEL-28, were treated with a donor of H 2 S (NaHS). CCK-8, scratch assay, flow cytometric analysis, western blotting and transmission electron microscopy (TEM) were performed to explore the effects of H 2 S on cell behaviors. : Treatment with NaHS inhibited cell proliferation, migration and division, while it could induce cell apoptosis and autophagy in melanoma cell lines. Moreover, NaHS significantly decreased the expression of p-PI3K, p-Akt and mTOR proteins. Furthermore, insulin-like growth factor-1 (IGF-1), the activator of PI3K/AKT/mTOR pathway, could reverse the cell behaviors caused by NaHS. : Our results demonstrated that exogenous hydrogen sulfide could inhibit human melanoma cell development via suppression of the PI3K/AKT/mTOR pathway. Hydrogen sulfide might serve as a potential therapeutic option for melanoma. [ABSTRACT FROM AUTHOR]

This study employs first‐principles calculations to investigate the structural stability, electronic properties, and elastic properties of Co‐, Ni‐, Cu‐, and Mo‐doped β‐Si3N4. After optimizing the structure of each doped system, it can be determined that all systems are stable structures, as evidenced by the binding energy and forming energy. Then, the electronic properties of the doped systems are analyzed using the energy band and density of states. The findings reveal that the introduction of Co, Ni, and, Cu, reduces the energy bandgap compared to pure Si3N4. More notably, the doping of Mo eliminates the bandgap and results in strong metallicity in the doped systems. Moreover, all doped systems display magnetic moments. Finally, the investigation of elastic properties shows that all doped structures are ductile. The doping of Co, Ni, Cu, and Mo metals improves the toughness of Si3N4. In addition, the doping change of Co is the most obvious. These findings provide a theoretical foundation for future research on the preparation of ductile Si3N4 ceramics. [ABSTRACT FROM AUTHOR]

The TiB x /Ti x Ni y /TiC reinforced Ni60 composite coatings were successfully prepared on the surface of 35CrMoV substrate using the laser cladding technology by adding different content of LaB 6 (0, 0.5, 1.5, 2.5 wt%) powders into the mixture of TC4 (Ti6Al4V) and Ni60 (94 wt% Ni60, 6 wt% TC4). The phase composition, microstructure, element distribution and chemical composition of the cladding layer were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) with energy spectrum analysis (EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), respectively. The reinforced phases in the cladding layer were mainly composed of TiB 2 , TiC, TiB, Ti 2 Ni, NiTi and Ni 3 Ti. The addition of LaB 6 did not affect the phase composition, but the grains are obviously refined and the distribution of Ni, Cr and Ti elements is uniform at the addition of 1.5 wt% LaB 6 addition. The cladding layer obtained excellent tribological and mechanical performance with the addition of 1.5 wt% LaB 6 , and the hardness, average friction coefficient and wear volume of the cladding layer reach 808 HV 1 , 0.183, and 8943 μm3, respectively. The reasonable addition of LaB 6 significantly improves the friction and mechanical properties of the cladding layer. [ABSTRACT FROM AUTHOR]

Abstract This paper provides a review on the current research developments in high temperature solid-lubricating materials. We first briefly discuss fundamental of high temperature solid-lubricating materials, including design strategies of a low friction coefficient, a high wear resistance, a wide environment range, and how to construct high temperature solid-lubricating materials. And then the review highlights progress in the design and exploration of high temperature solid-lubricating coatings (monolithic coatings, multiphase coatings and self-adaptive coatings) and composites (metal, intermetallic and ceramic matrices high temperature solid-lubricating composites). Finally, we shortly introduce practical applications and trends of high temperature solid-lubricating materials in the future. These developments offer new avenues to both intensify the understanding of high temperature tribology and expand the diversity of practical applications. Highlights • An overview about high temperature solid-lubricating materials is presented. • This review highlights progress in monolithic, multiphase and self-adaptive coatings. • Metal, intermetallic and ceramic matrices high temperature solid-lubricating composites are reviewed. • Practical applications and future trends of high temperature solid-lubricating materials are shortly introduced. [ABSTRACT FROM AUTHOR]

Abstract This paper is aimed to evaluate the high temperature tribological behaviors of CoCrFeNiNb x eutectic high entropy alloys which would be highly-promising candidates for high-temperature applications. The effects of testing temperature and material structure on the friction and wear properties are investigated. The CoCrFeNiNb x alloys display a low harness decrement rate about 35% from room temperature to 1000 °C, indicating good softening resistance. The main wear mechanisms are abrasion wear at room temperature, change to adhesion wear at 400 °C, and translate into oxidation wear and mechanical wear over 600 °C. The wear rates increase from room temperature to 400 °C and decrease afterwards. The effects of material structure are dominated by the hardness of alloy, the content of chemically active Nb element and the structure of oxidized tribo-layer. The compact oxidized tribo-layers with excellent anti-wear properties are formed on the worn surface of CoCrFeNiNb 0.65 and CoCrFeNiNb 0.8 alloys at 800 °C, leading to extremely low wear rate. Highlights • Tribological behaviors of CoCrFeNiNb x alloys at elevated temperatures are studied. • CoCrFeNiNb x eutectic high entropy alloys possess excellent softening resistance. • Wear rate increases from room temperature to 400 °C and decreases afterwards. • Oxidized tribo-layers with excellent anti-wear properties are formed at 800 °C. • Effects of material structure on wear behaviors and mechanisms are investigated. [ABSTRACT FROM AUTHOR]

In the vicinity of the top dead center of a diesel engine, the piston rings operate in a low-speed, high-load, and high-temperature environment, which is detrimental to the formation of an effective lubrication oil film. Consequently, it presents significant challenges for predicting the tribological characteristics of the piston ring-cylinder liner friction (PRCL) assembly. This study explores the micro-friction behavior of PRCL assemblies near the top dead center in engines using the molecular dynamics approach. The tribological characteristics of the PRCL, especially the microscopic wear mechanisms, were analyzed under various operating conditions such as ring sliding speed, ring back load, operating temperature, and lubricant supply amount. The liner surface morphology, liner wear, and lubricant film distribution were used to evaluate the tribological characteristics. It was determined that the lubricant supply amount has the most significant impact on the micro-friction behavior of the PRCL assembly. [ABSTRACT FROM AUTHOR]

In this paper, the tribological behaviors of 20 and 40 vol% in situ TiB 2 reinforced TiAl-based composites sliding against SiC balls were investigated in artificial sea water, and TiAl alloy was also studied as a comparison. The results showed that the TiAl-TiB 2 composites are lubricated in artificial sea water and TiB 2 is effective to improve the wear resistance of the TiAl alloy. Also, it was found that the tribological behaviors have a dependency on the applied loads and sliding speeds. Worn surface morphologies and composition together with electrochemical behaviors of the materials were evaluated and related to the tribological behaviors. [ABSTRACT FROM AUTHOR]

The development of HfC-SiC has been challenging due to difficulties in achieving sintering and satisfactory mechanical properties. However, this study aims to overcome these limitations by incorporating WC as an additive. SPS was employed to process HfC-SiC and HfC-SiC doped with 5 vol.% WC. The resulting samples were then evaluated for their oxygen content, relative density, Vickers hardness, bending strength, indentation fracture toughness, and microstructure. The Vickers hardness (20.50 ± 0.20 GPa), flexural strength (600.19 ± 84.00 MPa), and indentation fracture toughness (5.76 ± 0.54 MPa·m1/2) of HfC-30 vol.% SiC-5 vol.% WC ceramics are higher than HfC-30 vol.% SiC ceramics. Doping 5 vol.% WC in HfC-30 vol.% SiC not only reduces the oxygen content of samples but also produces the (Hf,W)C solid solution and refines the microstructures, which are the main reasons for the higher mechanical properties of HfC-30 vol.% SiC-5 vol.% WC ceramics. In summary, this study successfully addresses the challenges associated with HfC-SiC by incorporating WC as an additive, leading to improved mechanical properties and microstructures. [ABSTRACT FROM AUTHOR]

The high-entropy ceramic materials (Zr 0.25 Ce 0.25 Hf 0.25 Y 0.25)O 1.875 (H-0) and (Zr 0.2 Ce 0.2 Hf 0.2 Y 0.2 RE 0.2)O 1.8 (H-RE) (RE = La, Nd and Sm) with fluorite structure and homogeneous element distribution were prepared. With fluorite structure, fine grain size and high density, the H-0 and H-RE ceramics displayed low thermal conductivity, suitable thermal expansion coefficient, high hardness and fracture toughness. The effect of La, Nd and Sm on the mechanical, heat conductivity and heat expansion properties of high entropy ceramics were discussed. The single-phase high-entropy ceramic materials in this work are very suitable for application as thermal barrier materials. [ABSTRACT FROM AUTHOR]

• The crystallization of laser cladded amorphous coating mainly occurs in the overlapping area. • The overlapping area can be divided into the OTZ and the OHAZ. • The formation mechanism of overlapping areas and their impact on performance have been studied. The issue of crystallization during the laser cladding process poses a significant challenge to the application of amorphous coatings. In order to explore the practical application of Fe 41.5 Co 12.2 Cr 7.4 Mo 37.3 C 0.3 B 0.5 Y 0.4 Al 0.4 (at.%) amorphous composite coatings, this study fabricated coatings with different scanning speeds. The aim was to delve into their crystallization processes and assess the consequential effects on the coatings' properties. The study revealed that crystallization predominantly occurs in the coatings' overlapping region, which can be divided into two zones: the overlapping transition zone (OTZ) and the overlapping heat affected zone (OHAZ). The crystallization extent within the OHAZ is higher than in the OTZ, attributable to the disparate cooling rates characteristic of each region. With increasing scanning speed, the OHAZ gradually increases and the OTZ decreases. The coating prepared at 2000 mm/min has excellent corrosion resistance (polarization resistance 10,814.2 Ω · cm2) and wear resistance (wear rate (8.88 ± 0.378) × 10–6 mm3/N · m). [ABSTRACT FROM AUTHOR]

The tribological behavior of TiC/Ni composites is optimized by adding Ta, due to the improved oxidation resistance and hardness. The (Ti,Ta)C particles with core-rim structure are formed, and particle size decreases from 1.03 µm to 0.75 µm by adding 8 wt% Ta, and the hardness increases from 630.43 HV to 669.13 HV. At 20 N load, the primary wear mechanism is oxidation wear and the tribological property is influenced by oxidation resistance. At 50 N load, the main wear mechanism includes abrasive, adhesive, delamination and oxidation wear, and the tribological behavior is mainly influenced by the hardness and oxidation resistance. [ABSTRACT FROM AUTHOR]

A novel silver nanoparticle (Ag NPs)/copper foam-based triboelectric nanogenerator (SC-TENG) was designed and fabricated to realize multiple applications during gas emissions. 1. Energy Harvesting. Pulsed airflow-driven SC-TENGs can convert the mechanical energy contained in high-pressure airflow into electrical energy. 2. Air Pressure Monitoring and High-Pressure Warning. SC-TENGs can monitor gas flow pressure in real-time, providing a self-powered warning system to prevent high-pressure hazards in industrial production. 3. Information Transfer. By adjusting gas flow pressure, SC-TENGs enable encrypted information transmission using Morse code, enhancing their application in secure data communication. [Display omitted] • SC-TENGs are fabricated to monitor the air pressure of high-pressure air streams in industrial production environments. • SC-TENGs can effectively harvest the significant mechanical energy contained in high-pressure gas streams. • The output and sensing performance of SC-TENGs is dramatically improved. • SC-TENGs can be utilized to fabricate a warning system to protect worker safety. • SC-TENGs can transmit messages in the form of Morse code. Abundant high-pressure exhaust gas is generated during industrial production processes. The direct release of this exhaust gas not only leads to energy dissipation but also increases the accident risk. Therefore, it is essential to utilize and monitor high-pressure exhaust gas. This study designed a triboelectric nanogenerator (TENG) driven by high-pressure pulse airflow to realize energy harvesting and pressure monitoring at the gas–solid interface. The silver nanoparticles (Ag NPs)/ copper foam (CF)-based TENG (SC-TENG) were fabricated and exhibited excellent output characteristics. Compared to the copper-based TENG, the short-circuit current and output power were increased by 68.72 % and 63.34 %, respectively, which could directly light up 111 light-emitting diodes (LEDs). Furthermore, the effects of pipeline mateal, valve material, preparation environment (AgNO 3 concentration), and air pressure were investigated to optimize the electric output of SC-TENG. The SC-TENG exhibited excellent pressure sensing capabilities and could be applied for rapid and sensitive long-term monitoring. Based on this, a wireless high-pressure warning system was designed to realize signal transmission and safety pre-warning. Lastly, a novel information encryption method based on pulse airflow was developed, and its potential applications in various fields were discussed. This work not only proposes a utilization and solution strategy for high-pressure exhaust gas issues to realize the principle of "turning waste into treasure", but also provides valuable insights into the extended applications of TENG technology. [ABSTRACT FROM AUTHOR]

A Ni60 cladding layer containing 1.6 wt% La 2 O 3 was prepared on 35CrMoV steel using an alternating magnetic field-assisted laser cladding technique. The microstructure, phase composition, microhardness, and tribological properties of the composite coatings were characterized. Based on experimental results, the main components of the 1.6 % Ni60 + La 2 O 3 cladding layer are γ-(Fe,Ni), Cr 23 C 6 , FeNiSi, Ni 3 B, Ni 4 B 3 and Cr 2 B. The EBSD analysis reveals that the increase in intensity of the alternating magnetic field leads to a significant refinement in the average grain size of the cladding layer, thereby greatly enhancing microstructural uniformity. The average grain sizes of the layers with 0–15 mT magnetic field intensity are 28.515 μm, 26.076 μm, 23.878 μm and 18.337 μm, respectively. The TEM bright field images reveal that the enhancement of magnetic field intensity facilitates the precipitation of γ′ within the cladding layer. Friction and wear experiments demonstrated that a Ni60 composite coating containing 1.6 % La 2 O 3 exhibited superior friction and wear performance at a magnetic field intensity of 15 mT due to its highest average hardness (608.97 HV 1), lowest friction coefficient (0.394), and excellent wear morphology. • Solute segregation is reduced and microstructure uniformity is improved under the influence of 15 mT. • The intensity of strong <001> texture parallel to the tectonic direction decreases with the increase of magnetic field intensity. • The coherent strengthening of the γ' phase and matrix phase improve the high temperature mechanical properties. • The 15mT cladding layer has excellent tribological properties, which are reflected in the average hardness of 608.97 HV 1 and friction coefficient of 0.394. [ABSTRACT FROM AUTHOR]

• Ultrasonic vibration-assisted laser cladded Fe-based amorphous coatings were fabricated. • The mechanism of ultrasonic vibration on amorphous coatings was elucidated. • The evolution pattern of ultrasonic vibration on crystal and amorphous was investigated. In order to investigate the influence of ultrasonic vibration (UV) on microstructural evaluation of amorphous coating, the Fe-based amorphous (Fe 41.5 Co 12.2 Cr 7.4 Mo 37.3 C 0.3 B 0.5 Y 0.4 Al 0.4) coatings with and without UV were fabricated by laser cladding technology. The microstructure and corrosion resistance of the coatings were studied in detail to understand the mechanism of the UV on amorphous coatings. It can be found that the cavitation effect generated by UV refines and breaks the columnar crystals at the interface. Compared to the coatings without UV, the average length of columnar crystals of coatings with UV decreases by 57.52 %, reducing from 25.26 ± 5.89 μm to 10.73 ± 3.91 μm. In addition, the sound pressure gradient drives the accelerated flow of the molten pool, resulting in a flow velocity of up to 0.134 m/s. The acoustic streaming effect of UV promotes the uniform distribution of elements and inhibits the segregation of the intermetallic compounds, which increases the amorphous content from 68.5 % to 75.3 %. The acoustic streaming and cavitation effects refine the microstructure and increase the amorphous content by using of UV, which contributes to improve the corrosion resistance. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a series of ZrO2 matrix high-temperature self-lubricating composites were prepared by hot-press technique. The effect of Mo and Ag on the friction and wear behavior of the ZrO2(Y2O3)–Ag–CaF2–Mo composites in a wide temperature range was investigated. The XRD results showed that CaMoO4 formed on the worn surface above 400°C. The excellent lubrication performance of CaMoO4 endowed the low coefficient of friction of the ZrO2(Y2O3)–Ag–CaF2–Mo composites at high temperatures. The ZrO2(Y2O3)–10Ag–10CaF2–10Mo composites showed favorable wear resistance at all the tested temperatures which was attributed to the combined action of hardness and phase transformation. [Copyright &y& Elsevier]

The development of osteochondral composites that simultaneously exhibit superior load-bearing performance and lubrication properties remains a significant challenge. In this investigation, a novel hard-soft composite material, which utilizes porous Si 3 N 4 ceramics as a structural support and PVA-CBA (synthesis by condensation of polyvinyl alcohol and 4-formylbenzoic acid) hydrogels as a lubrication, was fabricated via impregnating the hydrogel into porous ceramics, namely Si 3 N 4 /PVA-CBA composites. It demonstrates strong interfacial bonding, comprising macro-micro scale mechanical interlocking and molecular scale chemical crosslinking. The developed material exhibits high mechanical strength (∼ 103.2 MPa and ∼ 1500 % larger than the corresponding value of porous Si 3 N 4 ceramics), low friction and wear (∼ 0.21 under 10 N load and 10 Hz frequency), and favorable cell adhesion and proliferation. This provides an effective strategy for designing hard-soft composite material in the osteochondral repair field. [Display omitted] [ABSTRACT FROM AUTHOR]

Soybean protein isolate (SPI), a promising biomass resource to substitute petroleum-based chemicals, has been widely employed to prepare biobased board adhesives due to abundant availability, environmental compatibility, and rich functionality. However, pure SPI-based adhesives exhibit poor mechanical properties and high water absorption, which limit their practical application. In this work, dopamine-functionalized hexagonal boron nitride (PDA-BN) and carboxymethylated lignin (CAL) were introduced to serve as fillers and reinforcers to cross-link with SPI. The wet and dry shear strength of resultant adhesive increased by 172% and 64.3% to 1.58 MPa and 2.07 MPa, respectively, compared to the pure SPI-based adhesive, surpassing the performance of a vast of different SPI-based adhesives. The SPI-based adhesive also demonstrated enhanced water resistance, flame retardancy, and mildew resistance. These improvements can be attributed to the dense covalent and noncovalent intermolecular interactions and improved compatibility between PDA-BN and the SPI matrix. • A novel SPI-based adhesive with enhanced properties was prepared by adding PDA-BN and CAL as fillers and reinforcers. • The wet and dry shear strength of the adhesive increased by 172% and 64.3%, respectively. • The adhesive also showed improved water resistance, flame retardancy, and mildew resistance. [ABSTRACT FROM AUTHOR]

In this work, a tungsten carbide (WC)-containing silicon oxycarbide (SiOC) glass-ceramic was prepared from WC-filled polysiloxane via pyrolysis and subsequent spark plasma sintering (SPS). The sintering behavior of SiOC was investigated by monitoring the densification temperature and shrinkage displacement. The phase composition and microstructure of ceramics were characterized by using FTIR, XRD, SEM, Raman spectrum, and optical microscope. It was shown that upon increasing the sintering temperature from 1400 °C to 1600 °C, the densification of ceramics was further improved, and the disorder of free carbon in SiOC was linearly decreased with sintering temperature. In addition, it was found that the incorporation of WC particles was effective to reinforce the mechanical properties of ceramics, and relevant strengthening mechanisms were discussed here. Finally, a correlation between phase composition, microstructure, and macroscopic performances of SiOC glass-ceramics was successfully derived. [ABSTRACT FROM AUTHOR]

Ceramic design based on reducing friction and wear-related failures in moving mechanical systems has gained tremendous attention due to increased demands for durability, reliability and energy conservation. However, only few materials can meet these requirements at high temperatures. Here, we designed and prepared a Sn-containing Si 3 N 4 -based composite, which displayed excellent tribological properties at high temperatures. The results showed that the friction coefficient and wear rate of the composites were reduced to 0.27 and 4.88 × 10−6 mm3 N−1 m−1 in air at 800 °C. The wear mechanism of the sliding pairs at different temperatures was revealed via detailed analyses of the worn surfaces. In addition, the tribo-driven graphitization was detected on the wear surfaces and in the wear debris, and the carbon phase was identified by SEM, TEM, and Raman spectrum. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carboxymethylation of lignin created more reactive sites to form hydrogel. • Incorporation of PDA@BN in the hydrogel improves the heat dissipation capability. • Employment of 3-ABA imparts the hydrogel with re-crosslinkable ability. • The recrosslinked hydrogel maintains excellent temperature resistance. In this work, a series of re-crosslinkable hydrogels comprising carboxymethylated lignin, PVA and 3-aminophenylboronic acid (3-ABA) was successfully synthesized. Incorporation of polydopamine (PDA) coated boron nitride (PDA@BN) endowed the hydrogel with significantly improved heat dissipation ability, mechanical strength and swelling resistance. The hydrogel containing 20 % of PDA@BN, namely Gel-20 %BN displayed an initial degradation temperature of 131 ℃ and a high thermal conductivity of 3.74 W/m·K, surpassing a plethora of different biobased hydrogels. Gel-20 %BN maintained stable morphology even under continuous heating at 200 ℃ for 15 min and exhibited low surface temperatures without undergoing melting or decomposition, thus demonstrating remarkable heat dissipation capability. The re-crosslinked hydrogel, referred to as Re.Gel-20 %BN, retained similar performance to Gel-20 %BN, maintaining excellent heat dissipation characteristics and stability at 130 ℃ over an extended period. Further investigation is warranted to explore degradation or recovery methods of this hydrogel in reservoir conditions, aiming to minimize the environmental impact of petroleum extraction and contribute to a greener and more sustainable oil production process. [ABSTRACT FROM AUTHOR]

In the field of marine engineering, the application of Cu-containing antibacterial high-entropy alloys (HEAs) are inevitably subjected to the damage of both wear and corrosion. However, there is a lack of the fundamental understanding of the effect of Cu distribution on the tribo-corrosion mechanisms of alloys in marine environments. In this study, the working conditions of the alloy in a standard 3.5 wt% NaCl solution were simulated to investigate the tribo-corrosion behaviour of CoCrFeNiCu 0.3 HEAs with different distribution states of Cu. The focus was put on the effect of copper distribution on the tribo-corrosion mechanisms of the alloy. The research unveiled a correlation where the progressive dissolution of the copper element led to an elevation in the friction coefficient of the alloy, concomitantly resulting in a reduction in the wear rate. Alloys with the homogeneous distribution of copper exhibited optimal tribo-corrosion resistance. Furthermore, the transition of the copper distribution from segregation to homogeneity led to a shift in the tribo-corrosion mechanisms of the CoCrFeNiCu 0.3 alloy from abrasive and corrosive wear to mild abrasive and oxidative wear. Moreover, the results demonstrated that by dissolving the Cu-rich phase and ensuring a homogeneous distribution of copper within the sintered alloy, the formation of corrosive microcouples and the detachment of oxidized debris were effectively suppressed. This promoted the formation of a protective chromium oxide layer in the groove region. The distribution optimization of copper towards homogeneity during the sintering process effectively enhanced the tribo-corrosion resistance of alloys. This work provides helpful guidance for material design and marine protection in the field of marine engineering. [ABSTRACT FROM AUTHOR]

The development of multifunctional films with high strength, biodegradability, and excellent thermal conductivity has drawn increasing interest. In this study, inspired by the unique hybrid structure of oysters, a nanophase-reinforced organic–inorganic hybrid structure was built using polydopamine modified boron nitride (BN@PDA), soy protein isolate (SPI), dialdehyde cellulose (DAC), and polyethylene glycol (PEG) to develop a strong soy protein film with multifunctionalities. The resultant films displayed excellent thermal diffusion ability and exhibited high tensile strength (24.03 MPa) and thermal conductivity (TC, 2.96 W·m−1·K−1) under low BN load (<0.5%). Meanwhile, the formation of non-covalent cross-linking and organic–inorganic hybrid structure endowed the films with superior flexibility. Importantly, owing to the selection of bio-based materials for preparation, the SPI-based films exhibited good biodegradability. It is believed that this study provides a creative perspective for the development of value-added multifunctional film materials and has good application prospects in advanced bio-based thermal conductive materials. • Polydopamine modified boron nitride (BN@PDA) was successful synthetized. • The resultant film presented good thermal diffusion ability and biodegradability. • The tensile strength of the resultant film increased by 245% to 24.03 MPa. • The thermal conductivity of the film was 2.96 W·m−1·K−1 at a low BN loading (<0.5%). [ABSTRACT FROM AUTHOR]

Ga-based liquid metals have promising applications as coolants and lubricants in the computer science, medical, and nuclear industries. In this paper, soft metal Cu was used as an additive to improve the lubricating performance of Ga-In-Sn. CuGa 2 phases were in-situ generated. At room temperature (RT, 25 °C) and 150 °C, GC0.2 and GC0.5 (Ga-In-Sn doped with 2 wt% and 5 wt% Cu) exhibited significantly better lubricating properties than Ga-In-Sn. At 150 °C, the wear rate of T91 steel lubricated by GC0.2 was 72.95% lower than that lubricated by Ga-In-Sn. At 300 °C, GC0.2 maintained a similar lubricating performance to that of Ga-In-Sn. The lubrication mechanism showed that the change in lubricant characteristics and friction film were the main factors to improve the lubricity. • Novel Cu-doped gallium-based liquid metals were successfully prepared. • CuGa2 phases could be in-situ generated in Cu-doped liquid metal. • GC0.2 exhibited outstanding lubrication performance at RT∼300 °C. • The change of lubricant characteristics and friction film improved the lubricity. [ABSTRACT FROM AUTHOR]

As a two-dimensional nanomaterial, Ti 3 C 2 T x MXenes can form a stable friction protective film on the matrix surface, which can effectively improve the anti-friction and anti-wear properties of grease under variable load, variable frequency, variable temperature and constant conditions. In this work, the friction coefficient and wear rate of the grease doped with 2 wt% Ti 3 C 2 T x are 27% and 56% lower than those of the base grease under the friction conditions of 50 °C, 100 N and 20 Hz, respectively. The grease doped with 2 wt% Ti 3 C 2 T x can withstand greater stress and its structure is more stable, which is proved by rheological tests. [ABSTRACT FROM AUTHOR]